.. _read_data_rt:

read_data_rt
------------------------------------------
This function reads the **real-time output data** from the robot controller.  
It retrieves the latest output structure containing motion, torque, and system states  
configured by :ref:`set_rt_control_output <set_rt_control_output>`.

Typically used inside a **real-time loop** after :ref:`start_rt_control <start_rt_control>`  
to continuously monitor joint positions, velocities, or external torques.

**Definition** |br|
``DRFLEx.h`` within class `CDRFLEx`, public section

.. code-block:: cpp

   LPRT_OUTPUT_DATA_LIST read_data_rt() {
       return _read_data_rt(_rbtCtrlUDP);
   };

**Parameter** |br|
None

**Return**

.. list-table::
   :widths: 25 75
   :header-rows: 1

   * - **Value**
     - **Description**
   * - LPRT_OUTPUT_DATA_LIST
     - Pointer to the structure containing all RT output data fields |br| 
       defined by :ref:`get_rt_control_output_data_list <get_rt_control_output_data_list>`.

**Example**

.. code-block:: cpp

   #include <chrono>
   #include <cstring>
   #include <thread>

   drfl.connect_rt_control("192.168.137.100", 12347);

   std::string version = "v1.0";
   float period = 0.001f;  // 1 msec
   int lossCount = 4;

   // Configure input/output streaming
   drfl.set_rt_control_input(version, period, lossCount);
   drfl.set_rt_control_output(version, period, lossCount);
   drfl.start_rt_control();

   // Real-time reading loop
   while (true) {
       // Copy the whole frame in one operation. Copying field by field leaves
       // the buffer free to be overwritten between copies, so the fields can
       // come from different frames.
       RT_OUTPUT_DATA_LIST frame;
       memcpy(&frame, drfl.read_data_rt(), sizeof(frame));

       printf("Joint 1 Pos: %.1f  Vel: %.1f  Torque: %.1f\n",
              frame.actual_joint_position[0],
              frame.actual_joint_velocity[0],
              frame.actual_joint_torque[0]);

       // Custom condition to break the loop
       if (frame.actual_joint_position[0] > 30.0f)
           break;

       // Sleep for the RT period
       std::this_thread::sleep_for(std::chrono::milliseconds(1));
   }

   drfl.stop_rt_control();
   drfl.disconnect_rt_control();

In this example, the function continuously retrieves and prints  
the current joint position, velocity, and torque from the real-time stream.

**Tips**

- Always call this function **after** RT streaming is started using :ref:`start_rt_control`.  
- The returned pointer is never null, so a null check is not a validity test. |br|
  The buffer it refers to is overwritten as new frames arrive, so a frame read field by field can mix values from two packets. Copy the whole structure in one operation, as the example does, and work from the copy.
- Use ``memcpy`` or direct indexing to copy data safely inside the loop.  
- For visualization, store data into arrays or send to a logger in real time.